1. Field of the Invention
L-Isoleucine is an important component for parenteral and enteral nutrition and complex amino acid preparations. The present invention involves an improvement to a process for producing L-isoleucine by fermentation.
2. Description of the Prior Art
It is known that in order to impart L-isoleucine productivity to microorganisms belonging to the genus Brevibacterium or the genus Corynebacterium, it may be sufficient for the microorganisms to have reslstances to .alpha.-amino-.beta.-hydroxyvaleric acid (hereafter simply referred to as AHV), etc. (Published Examined Japanese Patent Application No. 20316/73, U.S. Pat. No. 3,767,529). It is also known that the productivity of L-isoleucine may be improved by imparting to the microorganisms, in addition to the above-mentioned chemical resistances, O-methylthreonine resistance, .beta.-hydroxyleucine resistance or trichloroalanine resistance, and by imparting thereto auxotrophy for purine type substances or lysine, etc. (Published Examined Japanese Patent Applications Nos. 21077/76, 4629/77, 29998/81 and 3035/81, and Published Unexamined Japanese Patent Application No. 2687/82).
From a viewpoint of industrial production, it is of importance to improve the fermentation yield or accumulation of L-isoleucine.